Index: include/clang/Format/Format.h
===================================================================
--- include/clang/Format/Format.h
+++ include/clang/Format/Format.h
@@ -16,7 +16,6 @@
 #define LLVM_CLANG_FORMAT_FORMAT_H
 
 #include "clang/Basic/LangOptions.h"
-#include "clang/Basic/VirtualFileSystem.h"
 #include "clang/Tooling/Core/Replacement.h"
 #include "llvm/ADT/ArrayRef.h"
 #include <system_error>
@@ -27,6 +26,10 @@
 class SourceManager;
 class DiagnosticConsumer;
 
+namespace vfs {
+class FileSystem;
+}
+
 namespace format {
 
 enum class ParseError { Success = 0, Error, Unsuitable };
Index: lib/Format/Format.cpp
===================================================================
--- lib/Format/Format.cpp
+++ lib/Format/Format.cpp
@@ -22,6 +22,7 @@
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticOptions.h"
 #include "clang/Basic/SourceManager.h"
+#include "clang/Basic/VirtualFileSystem.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Allocator.h"